ABSTRACT
Objective To investigate the influence of the microscale attractive interaction on the elastic properties of DNA film in multivalent ion solutions. Methods Kornyshev's electrostatic zipper model was employed to describe the interaction energy between the DNA strands. The thought experiment method and macroscopic continuum bar model were combined to predict the stress-strain relationship, prestress, and elastic modulus of the DNA biofilm.Results Given the packing conditions, the DNA film exhibited a tensile prestress and negative elastic modulus. The prestress of the DNA biofilm ranged from -1.52 MPa to 1.17 MPa, and its elastic modulus ranged from -4.2 MPa to 64 MPa. Conclusions In contrast with monovalent solutions, the microscopic attractive interactions in multivalent solutions caused the elastic properties of the DNA film to exhibit a non-monotonous relationship with the variation in the packing density and salt concentration. The tensile elastic properties were significantly different from the compressive ones, and the tensile/compressive prestress as well as the positive/negative elastic modulus transformed each other. These results can contribute to understanding the mechanism of viral replication and provide references for gene detection and gene therapy.
ABSTRACT
Cell-substrate interactions are relevant for a number of biological and clinical applications e.g. to determine the effectiveness of medical implants. Cells are natural transducers that respond to and sense signals originating in their microenvironment. One important cell signaling mechanism is known as chemo-mechanical transduction. This refers to the use of external mechanical cues to initiate internal biochemical cellular processes and vice versa. One key factor to characterize and understand these interactions is the evaluation of the mechanical forces present at the cell-substrate interface. Recent advances in the micro and nanotechnology fields have allowed the development of new tools for the measurement of cellular and tissue forces. These tools have provided a means to study extremely low cellular and subcellular forces (pN-µN) as well as detailed small-scale tissue mechanics. This paper will review some of the most significant approaches to characterize the mechanical properties of cells and tissues at the micro-scale. Material properties, device fabrication, and design issues will be discussed.
Las interacciones célula-sustrato juegan un papel fundamental en gran número de aplicaciones biológicas y clínicas. Las células son transductores naturales que sensan y responden a señales en su entorno fisiológico. Uno de los mecanismos más importantes empleados en la caracterización de interacciones celulares es la transducción químico-mecánica, la cual se basa en la implementación de señales externas que se aplican a la célula con el fin de inducir diversos procesos bioquímicos al interior de ésta y viceversa. Los avances alcanzados en el campo de la micro y nanotecnología han permitido el desarrollo de nuevas herramientas para medir fuerzas a nivel celular o incluso sub-celular (pN-µN), y dilucidar la mecánica de los tejidos en la escala micrométrica. La presente revisión literaria describe algunos de los micro-dispositivos empleados actualmente para caracterizar las propiedades mecánicas de las células y tejidos en la micro-escala.